T. H. Bell is a mild-mannered man who understandably has kept a low profile as secretary of education under a president who promised to abolish the department Bell heads. But I have a hunch that Ted Bell is riding one of the big issues of 1984 politics--an issue that can make things tough for both Bell's boss, Ronald Reagan, and the leading Democratic presidential hopeful, Walter F. Mondale.

The issue, of course, is education-- but more pointedly what the United States is going to do to about the "rising tide of mediocrity" that the National Commission on Excellence in Education, appointed by Bell, said last month is threatening to engulf our schools and nation.

Bell is launching a series of regional meetings (the first was held May 13 in East Lansing, Mich.) aimed at "lighting a fire under the legislatures" in 1984 to improve teachers' training, standards and pay, and to toughen the curricula of the country's schools. The flames of that fire already are lighting up the country.

That's not just my gut feeling, but the judgment of Robert Teeter, the Detroit-based Republican pollster. He told me that "You can see in the data that education is becoming a more and more important issue, involving people's concerns for their children's economic futures and the country's competitive position." In its new and more potent form, he said, there is heavy emphasis on "academic quality, competency and accountability."

Those were the keynotes of the recent commission report, one of a spate of studies helping focus this issue for public debate. Reagan responded by talking about prayer in public schools and tuition tax credits--issues that Teeter said are tangential to the rising public concern. Reagan also disparaged the federal role in education in such sweeping terms that Mondale was able to charge in a speech last week that the president had "turned his back on the country, its children and its future." Instead of cutting back federal aid to education, as Reagan has tried repeatedly to do, Mondale said there should be a huge increase: $11 billion a year.

Bell strikes a middle ground. He defends existing federal aid, saying the programs targeted on poor and handicapped children have been a "demonstrated success." But he contends that the American taxpayers will not support the needed additional investment in education--by any level of government--"until we get the kind of changes the commission talked about" to stiffen the intellectual standards for both teachers and pupils.

He has thrown his support behind a basic change in the method of paying teachers. He favors paying incentive salaries for "master teachers." This would help attract the best college students into teachingand slow the drain of talented teachers into business and industry, he says.

Bell invited Tennessee Gov. Lamar Alexander, a Republican, who is pushing the "master teacher" plan in his state, to be a featured witness at the East Lansing hearing. Bitter opposition from the Tennessee Education Association sidetracked Alexander's proposal on a 5-4 vote in the state senate education committee last month. But it will be back on the agenda there in 1984--and, Bell hopes, in many other states as well.

The "master teacher" program is no panacea for all our education ills. But a poll taken by Peter D. Hart for the Tennessee citizens' group backing Alexander's proposal bears out Bell's basic contention that the teachers' unions may have to accept pay reforms and accountability if the schools are to gain new funds. Hart found, for example, that only 13 percent of those polled would support a tax increase to pay for across-the-board improvement in teachers' salaries. But 57 percent said they would support a tax increase to finance salaries "based on merit and geared to rewarding teachers who meet higher standards of competence." About 61 percent endorsed Alexander's specific proposal for adding a penny to the sales tax to finance his version of the "master teacher" plan.

Hart, as it happens, is Mondale's pollster, too. And Mondale is very close to the National Education Association, which, since 1969, has adamantly opposed any form of merit pay based on "instructional performance."

NEA's contention is that there is no objective measure of teacher competence and that the imposition of differential pay would just cause dissension and wreck morale among teachers. But when Hart put those exact arguments to the voters in his Tennessee survey, they were rejected by a 56-24 margin.

Mondale, as everyone knows, seeks and expects the NEA endorsement in October. He proposed dozens of programs in his lengthy statement on education last week, but said nothing about merit pay. A spokeswoman said that Mondale thinks that kind of decision should be made by the local community.

For Mondale, as for Reagan, Ted Bell's issue may prove a litmus test of presidential stature.